fix(ui): import hierarchical session store from correct module

Agent-Logs-Url: https://github.com/MervinPraison/PraisonAI/sessions/2391890c-5d2f-4a45-b424-67a3861f5484

Co-authored-by: MervinPraison <454862+MervinPraison@users.noreply.github.com>

Author: Copilot

src/praisonai/praisonai/ui/_aiui_datastore.py

@@ -17,7 +17,7 @@ class BaseDataStore:
 
 try:
     from praisonaiagents.session import SessionStoreProtocol
-    from praisonaiagents.session.stores import get_hierarchical_session_store
+    from praisonaiagents.session import get_hierarchical_session_store
 except ImportError:
     # Fallback when praisonaiagents not available
     SessionStoreProtocol = None
@@ -97,4 +97,4 @@ async def get_messages(self, session_id: str) -> list[dict[str, Any]]:
         try:
             return self._store.get_chat_history(session_id) or []
         except Exception:
-            return []
+            return []